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Ethics of processing for astroimages?


iwatkins

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Hi All,

As I start to get into the imaging side I have a question. It's probably been asked before but I cannot find anything through searching.

When post processing an astro image what is the "done thing" with regards to artistic licence?

I spent a couple of years running a photo studio. I concentrated on product photography and model photography. For product work, you have no licence. It must look like the product the client wants to sell. Yes, you could light it in a moody way etc. but when it came to processing the image you had no leeway really (obviously).

On the flipside, shooting models with the camera was only the start. You would then spend the next few hours in Photoshop removing blemishes, smoothing skin, generally improving the look of the person.

So, too totally different ways of tackling things.

Now I'm getting into astro imaging I'm unsure of what is "allowed" and what is "frowned upon". I've just finished reading "Make every photon count" (really excellent book) and there is no mention of the ethics at all. Histo stretching, saturation changes, sharpening, filters all seem OK.

Interested in peoples thoughts.

Cheers

Ian

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Sorry to answer a question with a few more questions...

Science or Art...?

Whats the purpose of a particular image...?

Are you iamging for yourself or the "wider world"...?

Personally for me it's always been "art" , pretty "pictures" and for "me"...

As long as its all my own Data....

Peter...

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Your own Data, you're free to do what you want with it.

I suppose if you're comparing images i.e. a competition perhaps? then you might want to declare how much "touching up" you did.

But I wouldn't worry.

Clearly the initial image is what you have to work with, so credit will always be due to the amount of work (focus, tracking , exposure etc) that has gone into it.

You'll be the only one who really knows that.

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I'm not sure there are any ethics really beyond acknowledging whether it's your own data or not ;)

How the images are processed is an individual thing - some aim to extract every last ounce of data from an image, some settle for a 'nice' picture (again subjective) some like bright colours, some like subdued colours and so on. All of this is subjective and unique to each imager :o

James

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I think the thing is to say something about the image and how it was created.

NB imagers usually state how they mapped their colour. Broadband imagers do the same; is it LRGB, RGB, HaLRGB? HaO111LRGB etc etc. Maybe also how any NB was applied. Eg Ha to red or Ha to red and lightly as luminance, etc. Or sometimes HaGB as in a recent, and excellent, M81. That way the audience knows what they are looking at.

When I use two focal lengths on the same image or add a comet from a different night I will always say that I've done that.

Everyone expects an imager to stretch the histogram at the bottom. Not much point in imaging if you don't! We are all in the business of making the invisible visible but not of inventing it.

A lot of us try to avoid changing one part of an image and not another (eg stretching a colour channel on one galaxy but not another) and might declare that we'd done so if we did.

Olly

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It's a tricky question, because virtually all the objects we are imaging are functionally invisible. That is we cannot observe them with the naked eye, and usually not at that level of detail even with a large scope.

So the question becomes are you trying to communicate science or art?

If science, then you can do what you like as long as you explain what you have done to the data. If you want to point out to people the star-forming regions in the outer arms of a galaxy, then any processing trick to highlight them is valid because you want to draw people's attention to the feature you are talking about. If you look at great 'communicating' astro-images from the pros, then they will sling in false colour, data from X-ray, UV or IR, or anything else that makes the point. Everyone knows it is not 'real'.

Curiously I think that art pictures impose more constraints because people are unfamiliar with these subjects and think that it is 'real' so extreme distortions (major colour shifts etc) seem to be less acceptable. People appeal to aesthetic principles of what 'looks' right, irrespective of how many photons of each wavelength are captured at each location.

I suspect that amateurs are more demanding of their data and more gentle with their visualisation than professional astronomers who are trying to answer a question.

old_eyes

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Well, I had not considered the question, but as one of my latest postings to the forum consists of two images cut and pasted together (to get both Saturn and its moons required different exposures) I guess I would come down pretty heavily in the 'anything goes' camp. And I would guess that almost every image on the forum has been 'adjusted' in some way, even if only by the addition of darks/flats/bias to remove the noise - which I would suggest is no different from improving your model shots.

My 2p ...

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Providing you're not intending to deceive then it's pretty much up to you. The reason I take images is to find out more about the subject. If that results in a pleasing picture then that's nice, but I regard that as a side-effect not the central goal. Obviously everyone else is entitled to their own views.

My personal philosophy is that I'll process images to bring out detail, reduce noise, enhance stuff that's already there. But I don't feel the need to add in things from other people's work or to paint in new information -= though I frequently merge images into panoramas. I have been known to cut'n'paste over blemishes (aircraft lights, satellite/meteor trails) that occur in the background but I want to keep the main subject as "natural" as I can.

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My view on it is this....

Reveal anything that is there any way you want, but don't add objects that aren't.

So, if you want to add diffraction spikes to spice up your image artistically, fine, but don't start adding extra background galaxies for example.

Also, dont plagarise other peoples images and add them to your own or pass them off as your own.

I may have missed a couple of things, but as far as I'm concerned anything else goes.

Rob

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"Know then, it is not the spoon that bends but you.."

As there's no contract -it's up to the photographer and what he/she wishes to convey. The observer can place no value or opinon but their own.

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I'm not sure there are any ethics really beyond acknowledging whether it's your own data or not ;)

How the images are processed is an individual thing - some aim to extract every last ounce of data from an image, some settle for a 'nice' picture (again subjective) some like bright colours, some like subdued colours and so on. All of this is subjective and unique to each imager :o

James

That pretty much covers it for me too, I believe you develop your own 'look' after a while with your images. I think an element of it is down to the software you use too but the real 'art' in imaging is the processing.

Tony..

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It seems I am in the same camp as most people here in that most of us are aiming for "pretty pictures" instead of scientific data. I am not trying to discover the exact emissions of objects, doing photometry, etc - I am trying to take a picture that I like. I share it to see what others think of it and because I like to see other people's pretty pictures so maybe there is someone out there that would like to see mine.

I also agree that astrophotography is an art, especially on the processing side as you can post the same data for 30 people to share and process and you will end up with 30 different looking pictures. Once you add in narrowband you will get even more variation as there are so many ways to combine them and generally it is understood that it will not look like it is "supposed" to as RGB might. Pretty much anything is game, in my opinion, for processing as long as its your data (or you are using shared data but state who took took it and kindly let you play with it). I use saturation, take out stars to process nebulas separate and then add the stars back in, remove airplane or satellite trails, occasionally add star spikes to make it pretty, etc, etc and expect that some form of that is done with almost any astrophoto.

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To me anything goes provided you don't add someone else's data to yours. As most deep sky objects are pretty well invisible to our eyes from a colour perspective, who is to say what they should look like? Obviously, there are some preconceived ideas of how certain objects should appear, for example one would expect the North America Nebula to be red in colour so a green version would be out of kilter with people's expectations but even that is up to you if you are taking the images purely for your own pleasure.

Even adding data from another image of your own is fine, for example taking a short exposure of the Moon followed immediately by a long exposure of Saturn just reappearing from occultation with the Moon is generally considered fair game as it's the only way to get the correct exposure of the two together.

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Personally my views are is that it is up to the person who took the data on how they process it. There are many techniques to get that hard data out and make it visible.

I try to give details on what I do when I process mine such as the tools used, channels and time.

Were I do draw the line is when the data is fabricated to decieve in terms of science, but thankfully not many people do that anymore.

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This is a really intersting question and cuts to the heart of what we do here in the imaging section so I felt that I had to reply to give my take on it.

I have my own ethics which I apply to my own processing but I think that broadly speaking, for portraying astro images here and elsewhere, any processing which helps to bring out existing but "hidden" detail is acceptable whereas adding something that is not already there is not.

As an example, for an image of a faint nebula, I would happily apply the use of stretching the histogram, using curves, sharpening, noise reduction, Dynamic background extraction to remove gradients, brightness and contrast, hue and saturation. Where I would most certainly draw the line is at using "piant" tools to paint in detail that isn't there - such as faint stars or bits of the nebula that I didn't manage to catch, perhaps because it was too faint for my camera. Another example of a tool that I wouldn't personally use is the Noel's Actions that can add diffraction spikes. If they are there then that's fine, but if I've been imaging with the refractor then I most certainly wouldn't add spikes. Much of the processing is actually compensating for the camera's inadequacies, light pollution, atmospheric distortion.

There is one exception to these personal rules of mine - I was asked by a friend to do a star field shot for him that looked a bit like the star field that used to be shown on the TV programme "The Old Grey Whistle Test" - famously with the Neon man kicking. On this occasion I did actually enhance and add star diffraction spikes to mimic the picture he wanted me to recreate. (He was very happy with his new desktop image) I wouldn't dream of parading it on this forum though as it's not what I would call a genuine image - more a piece of art.

Regards

John

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Another example of a tool that I wouldn't personally use is the Noel's Actions that can add diffraction spikes. If they are there then that's fine, but if I've been imaging with the refractor then I most certainly wouldn't add spikes.

Regards

John

I have no problem adding diff spikes on the occasional star as I'm not trying to be a scientist, and the way I see it, diff spikes are just an artifact, so you're not adding important stuff that's not there.

The question is, if you had diff spikes caused by the fact that you were using a scope with a secondary holder, and they were making a mess of the image to some extent, would you remove them?

Or would you remove blooming spikes that you get on some cameras?

Rob

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Photoshopped wolves howling at the moon are right out.

Seriously though - the process of calibration, combining and teasing out as much detail as you can takes up hours before you even start to worry about anything else.

Some people don't like diffraction spikes, some don't like hubble palette images or those pink stars you see on some colour schemes.

I say so long as you are happy with the image that is all that counts, but fellow imagers are a friendly bunch and will always find good things to say about your image along with the (hopefully) constructive criticism.

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Nothing wrong at all with trying to reproduce exactly what's there through clever use of filters and lenses and whatever other equipment.

Also nothing wrong with tarting it up a bit to something aesthetically pleasing to yourself - we see artistic license used all around us in daily life - so why not astronomy too?

Only thing I wasn't too hot on was a recent moon drawing that had been Photoshop'ed up a bit. Looked wierd to me - more like a Dahli landscape lol. But whatever floats your boat really ;)

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So Greg Parker and Noel Carboni are astro-artists then, not an astrophotography team?

Personally, I consider myself as an artistic astrophotographer....others may not agree ;)

To quote a James Bond villain....'names is for tombestones baby' :o:D:D

Rob

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I have no problem adding diff spikes on the occasional star as I'm not trying to be a scientist, and the way I see it, diff spikes are just an artifact, so you're not adding important stuff that's not there.

The question is, if you had diff spikes caused by the fact that you were using a scope with a secondary holder, and they were making a mess of the image to some extent, would you remove them?

Or would you remove blooming spikes that you get on some cameras?

Rob

Rob - if you want to do that - I wouldn't argue with it - I'm merely reflecting my own ethics and wouldn't want to judge anyone else on what they do - at the end of the day it's a hobby and if we enjoy it then that's fine, as long as we don't mislead others. As for removing spikes - no I wouldn't. I'm yet to image a target where it's been a problem - if it was then I might have to re-evaluate:)

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